Conditions, mechanism of formation and morphology of ferrite supersaturated with carbon (chernovite)

A study was made into the mechanism of formation and structure of a specific alpha-phase (chernovite) in a number of carbon and low alloy steels. It is shown that the chernovite constitutes a ferrite supersaturated with carbon and is formed directly from austenite in a subcritical temperature range in the form of plates or equiaxial grains. The isothermal tempering results in chernovite transformation into equilibrium ferrite and dispersed carbides and in a hardness decrease. Alloying elements promote an increase of hardness and decelerate chernovite tempering. The quantity of chernovite in the steel depends on the temperature of phase transition and carbon concentration. 10 refs.; 6 figs.; 2 tabs